1. Field of the Invention
The present invention is directed to a shoe having a high traction, replaceable, sole pad. The shoe is especially well suited for use by roofers and others working on steeply inclined surfaces.
2. Description of Related Art
Many devices have been developed over the years to improve the stability of roofers working on the inclined pitches commonly encountered. This is a problem that has worsened in recent years, particularly in the residential building market, as many newer homes are being designed with steeper roof pitches than had previously been used in residential construction.
The different types of traction-improving devices developed for use by roofers are numerous. Many years ago, steel or metal shoe attachments were prevalent in the patented art, which attachments generally had spikes or pointed spurs that would extend downwardly from the sole once the attachment was fastened in place. Some of the devices of this type were constructed such that the shoe would be maintained in a substantially horizontal position, and the device would have angled plates to engage the pitched roof surface and to support the shoe in a horizontal position.
Other patents evidence attempts to provide a sole or a shoe attachment that provides improved traction over a normal shoe sole. U.S. Pat. No. 2,628,437, to Forsythe, discloses an anti-slip shoe attachment which has a sole formed from a flexible sheet of coarse abrasive material. U.S. Pat. No. 5,259,125, to Gromes, discloses an attachment for the front part of a shoe having a sole made of indoor-outdoor carpet of a medium weave, that is said to provide improved traction for the wearer. That patent also discusses other various designs and devices previously proposed for use in aiding roofers to maintain better traction.
As further noted in the Gromes patent, asphalt roof shingles have been used extensively in roof constructions for a good number of years. The roof shingles have various grades of stone gravel embedded in a flexible, petroleum-based, sheet material. Care must be taken by the roofer not to damage the shingles, either by tearing or gouging the shingle, or by causing a large amount of the embedded gravel to be scraped off, during installation and thereafter in completing construction of a house or other building. Generally speaking, a hard or relatively rigid material that might otherwise provide acceptable anti-slip properties would not be suitable for use by roofers because such surfaces would be too prone to damaging the shingles.
Other anti-slip soles and shoe attachments have been developed for specific applications outside the roofing business. U.S. Pat. No. 4,924,608, to Mogoyne, discloses a replaceable anti-slip sole that is constructed of a non-woven synthetic, fibrous material. The shoe is intended to be used by maintenance persons such as floor cleaners, to provide traction on wet, slippery floors. Indeed, the anti-slip material is disclosed as preferably being the same material as is used on the cleaning machines themselves. While soles made of this material are disclosed as being durable, the surface on which these soles are used is not abrasive, but exactly the opposite, i.e., very slippery and substantially horizontal. The professed durability of the anti-slip material appears to be principally directed to the material's resistance to attack by chemicals and cleaning compounds, and not a physical durability.
It is believed that such soles would not be suitable for use on a roofer's shoe, primarily due to the lack of durability if used on an abrasive working surface. Further, as noted in the Gromes patent, the problem facing roofers is not that the surface is inherently slippery, but rather the surface is presented to the roofer or other worker at steep inclines. Materials that provide increased traction on wet floors may not perform adequately on an abrasive, but angled, surface.
U.S. Pat. No. 4,897,935, discloses a shoe attachment or an overshoe, principally for use on sloping and/or slippery ground. The non-slip surface is disclosed as being an open-celled foam of low density, defined in that patent as between 30-40 kg/M.sup.3. The non-slip layer is disclosed as being replaceable, and is secured to an intermediary foam layer of slightly higher density, by an adhesive. The open-cell, low density non-slip surface of this device would not be suitable for use on a roofer's shoe, from the standpoint of the lack of durability, and also because it is believed that the layer would not provide sufficient traction, and instead would tear or shred when placed in contact with asphalt shingles, once higher shear forces are applied.
The surfaces that a roofer encounters, such as plywood sheathing, a tar paper interlayer, and the asphalt shingles, are not themselves inherently slippery. It is the slope at which these surfaces are presented, and the fact that the roof is at a considerable distance above ground, that make improved traction on angled, ofttimes abrasive, surfaces so important for the shoe sole. The sole must also be reasonably resistant to wear when used on these sloping abrasive surfaces. Despite the prior attempts to fashion a shoe or shoe attachment suitable for use by roofers, a strong need persists in this field for a shoe that provides a combination of high traction and durability at a reasonable cost, thus making it economically feasible for roofers to buy and wear the shoes, or for a company to outfit its workers with such shoes.
One factor that appears to have been largely overlooked in the design of shoes for roofers is that a somewhat greater expense for the shoes over the long-term can be justified if the shoe provides such good traction that the efficiency of the roofer or other worker is improved due to the ability to more quickly and ably move about on the pitched surface. The above-noted Gromes patent and other patents directed to attachments for roofers' shoes tacitly acknowledge that additional expense may be justified in attempting to improve safety, but do not directly address worker efficiency. These patents approach the problem by providing devices that are not a part of the shoe, but are instead attachments to be worn over the shoe while the person is working on the roof. Thus, while better traction might be provided, the attachments add weight to the shoe, generally decrease the flexibility of the footwear, and may also prove to be unwieldy when the worker attempts to move around on the roof.
As noted previously, the principal problem with maintaining traction on a shingled surface is not that the shingles are inherently slippery, but that they are presented on a slope, and, particularly in new residential construction, the roofs have, in recent years, been designed to have even steeper pitches. Various materials were assessed in developing the shoe design and sole pads of the present invention, including the principal types of shoes currently worn by roofers.
Conventional athletic shoes (or tennis shoes) and work boots are the prevalent types of footwear worn by roofers today. Those generally have high density, solid, hard rubber soles, which provide a fairly durable shoe, in terms of wear and sole life, when used on the types of surfaces encountered by roofers. However, such soles are problematical in terms of the traction they provide. The relatively hard, solid soles can tend to lose traction as the wearer moves around on the roof, as the material is not resilient enough to "grab" or "bite into" the shingles and other roofing material. Where such a material does "grab" the shingle, it is generally at the expense of gouging the shingle, i.e., exerting force that has the result of dislodging the stone gravel making up the upper surface.of the shingle. It is not uncommon that courses of shingles have to be replaced because they have been gouged. Other hard, solid sole materials, such as shoe leather, would have substantially the same disadvantages.
Open-celled foams may have reasonably good anti-slip properties, from the standpoint of being resilient and thus being able to grab or grip the roofing surfaces. Low density, open-cell foams, of the type disclosed for use as the anti-slip surface for the shoe attachments in the above-noted U.S. Pat. No. 4,897,935, to Fel, would not, however, be sufficiently durable to evaluate their anti-slip properties, as the low density foams would be quickly shredded and worn away by the asphalt shingles. Higher density open-cell foams would be only slightly more durable, but the open-cell nature of the material causes even the higher density material to wear rapidly, as well. Such materials are not sufficiently durable, even if made to be replaceable, to be suitable for use by roofers. The soles would have to be replaced possibly up to several times a day, thereby severely adversely impacting the worker's efficiency, and possibly making the shoe and sole itself cost prohibitive.